From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,37023471dc2e1934
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news2.google.com!news.germany.com!news.belwue.de!newsfeed.ision.net!newsfeed2.easynews.net!ision!newsfeed.arcor.de!news.arcor.de!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Custom model in gtkada?
Newsgroups: comp.lang.ada
User-Agent: 40tude_Dialog/2.0.15.1
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Reply-To: mailbox@dmitry-kazakov.de
Organization: cbb software GmbH
References: <3ndpd7br1nn9$.vkcrts8e898z.dlg@40tude.net>
 <20060614210028.GA18024@ws.max.zp.ua>
 <b6ehptggg0ol$.lebhfvkvarnm.dlg@40tude.net>
 <44917d39$0$4495$9b4e6d93@newsread2.arcor-online.net>
 <xw8jxgsp30w8$.1llfb1lh4mohz$.dlg@40tude.net>
 <44941be9$0$11065$9b4e6d93@newsread4.arcor-online.net>
 <14e2r2ftir9ok.i8u1axnplx11.dlg@40tude.net>
 <449a432e$0$15869$bb6a4dc3@news.uunet.fr>
Date: Thu, 22 Jun 2006 10:31:20 +0200
Message-ID: <mgfz59ck9hje.18zecgqt5ze9w$.dlg@40tude.net>
NNTP-Posting-Date: 22 Jun 2006 10:31:20 MEST
NNTP-Posting-Host: 2d892a09.newsread2.arcor-online.net
X-Trace: 
 DXC==m4AgcgESC>F:^Y;boJ3Y0Q5U85hF6f;4jW\KbG]kaM8[NGU2GAcMG:F8R>5X@G[J2WRXZ37ga[7:n919Q4_`Vj9NZZj5LgkU<7
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news2.google.com comp.lang.ada:4898
Date: 2006-06-22T10:31:20+02:00
List-Id: <comp.lang.ada>

On Thu, 22 Jun 2006 09:16:22 +0200, Emmanuel Briot wrote:

> Dmitry A. Kazakov wrote:
>> I would expect callbacks be primitive operations of a tagged type rather
>> than pointers.
> 
> This is of course a design choice, and you can easily implement a small
> layer on top of GtkAda to do just that.
> The advantage with pointers is that you can add or remove callbacks during
> the life of a widget, which is harder to do with primitive operations where
> you need flags to know whether to react to the event or not. Also you can
> have multiple callbacks on the same signal, which, again, is harder to do
> with primitive operations.

Maybe, though I doubt that events were a right design decision (as a
notification mechanism).

Another point, a list of pointers to subprograms is in no way better than a
list of tagged objects (with primitive subprograms).

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de